1. Field of the Invention
The present invention relates to a light source device, and in particular, to a light source device in which light-emitting elements are provided on the side surfaces of light transmitting media, and the lights from the light-emitting elements are introduced from the side surfaces of the light transmitting media to the interiors thereof, and are outputted from end portions of the light transmitting media.
2. Description of the Related Art
In conventional optical communication systems, a technique has been used which transmits and outputs, by a light transmitting medium such as an optical fiber or the like, light which is emitted from a light-emitting element. Specifically, an LD (laser diode) is generally used as the light-emitting element, and the light outputted from the LD is incident on the end surface of the optical fiber and is introduced into the interior of the optical fiber.
The optical fiber is a long, thin, fiber-shaped body having a small diameter. Thus, a structure in which a plurality of optical fibers are used and the light output sides thereof are bundled together is applied to light sources requiring output of plural lights at a high density, e.g., illumination, exposure light sources for printers, light-emitting light sources for displays, and the like. However, when light enters from the end surface of the optical fiber, because the light-emitting surface area at the optical fiber side end surface of the LD is small, there are limits to the amount of light which is introduced into the optical fiber. Accordingly, the amount of light outputted from the optical fiber is also small. Thus, application to various uses such as illumination, exposure light sources of printers, light-emitting light sources of displays, and the like, is difficult.
Thus, as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 8-315984, a technique has been studied which utilizes, as a light-emitting element, an electric field light-emitting element called an electroluminescent (hereinafter, xe2x80x9cELxe2x80x9d) element which uses, in the light-emitting layer thereof, an inorganic or organic substance which emits light by voltage being applied. EL elements can be broadly classified into inorganic EL elements and organic EL elements, in accordance with the material used in the light-emitting layer. Among these, organic EL elements have the features that they are easier to manufacture than other light-emitting elements, thin and light-weight light-emitting elements can be formed, and organic EL elements can be driven at a lower voltage than inorganic EL elements. Thus, much attention is being paid to organic EL elements in particular. In JP-A No. 8-315984 as well, by using an organic EL element (more specifically, by providing an organic EL element so as to be wound on the periphery of a rod-like base member such as an optical fiber or the like), the surface area of light emission of the organic EL element with respect to the base material can be made large, and a larger amount of light can be introduced into the base member.
However, in the technique disclosed in JP-A No. 8-315984, because only a single optical fiber is used, only a single light is outputted, and the technique can only be used for limited applications.
The present invention was developed in order to overcome the above-described problems, and an object of the present invention is to provide a light source device which can output a plurality of lights by using light transmitting media, and which can supply light of a sufficient intensity to the respective light transmitting media.
In order to achieve the above object, a light source device of a first aspect of the present invention comprises: media for transmitting light that has been introduced into interiors of the media and outputting the light from ends of the media, the ends being disposed in a predetermined arrangement; light-emitting elements, each being disposed at at least a portion of a side surface of a respective one of the media, and each element comprising a transparent first electrode layer serving as an anode, a layer emitting light upon application of a voltage thereto, and a second electrode layer serving as a cathode, being layered successively; and a portion for applying voltage between the first electrode layer and the second electrode layer of each of the light-emitting elements.
In accordance with the first aspect of the present invention, each light-emitting element emits light when voltage is applied by the voltage applying section. The emitted light passes through the transparent first electrode layer, and is introduced into the interior of the light transmitting medium from the side surface of that light transmitting medium. Thus, light of a sufficient intensity can be provided to the light transmitting medium, as compared with a type of light transmitting medium in which light is incident onto the end surface thereof (hereinafter, xe2x80x9cend surface incident type light transmitting mediumxe2x80x9d). Note that the intensity of the light which is introduced into the interior of the light transmitting medium can be adjusted by adjusting the surface area of the light-emitting element on the side surface of the light transmitting medium.
The light transmitting medium transmits the light introduced therein, and outputs the light from the end surface thereof. At this time, the respective end portions of plural light transmitting media may be disposed in a predetermined arrangement such that the plural lights can be outputted from the light source device on the basis of this arrangement. In this way, plural lights can be outputted by using plural light transmitting media, and light of a sufficient intensity can be supplied to the respective light transmitting media. Thus, the light source device can be utilized in more applications than the conventional art.
In a light source device of a second aspect of the present invention, in the first aspect, the predetermined arrangement is one-dimensional or two-dimensional. In accordance with the second aspect, a plurality of lights which are disposed in a one-dimensional arrangement or in a two-dimensional arrangement can be outputted from the light source device. Namely, the light source device can be used as the light source of all types of apparatuses which require a plurality of lights in a one-dimensional arrangement or a two-dimensional arrangement.
In a light source device of a third aspect of the present invention, in the first or second aspect, the elements are a combination of plural types of light-emitting elements outputting lights of different wavelengths. In accordance with the third aspect, lights of plural wavelengths can be outputted in a predetermined arrangement (pattern) from the light source device. The light source device can be used as the light source of all types of apparatuses which require, for example, lights of wavelengths corresponding to red color, green color, blue color, and the like.
In a light source device of a fourth aspect of the present invention, in any of the first through third aspects, the voltage applying portion applies voltage independently to each of the plurality of light-emitting elements. In accordance with the fourth aspect, the light outputs from the plurality of light transmitting media can be controlled independently. Thus, the degrees of freedom increase, and the range of utilization of the light source device can be broadened.
In a light source device of a fifth aspect of the present invention, in any of the first through fourth aspects, the light-emitting elements are organic electroluminescent elements. In the light source device of the fifth aspect, organic electroluminescent elements, which are easier to manufacture than other light-emitting elements, are used as the light-emitting elements. Thus, the light source device can be made to be thin and light-weight, and driving at a low voltage is possible.